Periodically attempt to discover new wemo devices (#44361)

* Periodically attempt to discover new wemo devices

* Set self._stop=None after stopping the periodic discovery task

* Use the async_fire_time_changed test helper to simplify test_discovery

* Stop the pywemo registry outside of the async loop

* Add a comment describing why async_fire_time_changed is used

homeassistant/components/wemo/__init__.py

@@ -11,9 +11,12 @@ from homeassistant.components.binary_sensor import DOMAIN as BINARY_SENSOR_DOMAI
 from homeassistant.components.fan import DOMAIN as FAN_DOMAIN
 from homeassistant.components.light import DOMAIN as LIGHT_DOMAIN
 from homeassistant.components.switch import DOMAIN as SWITCH_DOMAIN
+from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import EVENT_HOMEASSISTANT_STOP
+from homeassistant.core import HomeAssistant, callback
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.dispatcher import async_dispatcher_send
+from homeassistant.helpers.event import async_call_later
 
 from .const import DOMAIN
 
@@ -90,7 +93,7 @@ async def async_setup(hass, config):
     return True
 
 
-async def async_setup_entry(hass, entry):
+async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry):
     """Set up a wemo config entry."""
     config = hass.data[DOMAIN].pop("config")
 
@@ -98,14 +101,16 @@ async def async_setup_entry(hass, entry):
     registry = hass.data[DOMAIN]["registry"] = pywemo.SubscriptionRegistry()
     await hass.async_add_executor_job(registry.start)
 
-    def stop_wemo(event):
+    wemo_dispatcher = WemoDispatcher(entry)
+    wemo_discovery = WemoDiscovery(hass, wemo_dispatcher)
+
+    async def async_stop_wemo(event):
         """Shutdown Wemo subscriptions and subscription thread on exit."""
         _LOGGER.debug("Shutting down WeMo event subscriptions")
-        registry.stop()
+        await hass.async_add_executor_job(registry.stop)
+        wemo_discovery.async_stop_discovery()
 
-    hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STOP, stop_wemo)
-
-    devices = {}
+    hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STOP, async_stop_wemo)
 
     static_conf = config.get(CONF_STATIC, [])
     if static_conf:
@@ -116,28 +121,31 @@ async def async_setup_entry(hass, entry):
                 for host, port in static_conf
             ]
         ):
-            if device is None:
-                continue
-
-            devices.setdefault(device.serialnumber, device)
+            if device:
+                wemo_dispatcher.async_add_unique_device(hass, device)
 
     if config.get(CONF_DISCOVERY, DEFAULT_DISCOVERY):
-        _LOGGER.debug("Scanning network for WeMo devices...")
-        for device in await hass.async_add_executor_job(pywemo.discover_devices):
-            devices.setdefault(
-                device.serialnumber,
-                device,
-            )
+        await wemo_discovery.async_discover_and_schedule()
 
-    loaded_components = set()
+    return True
 
-    for device in devices.values():
-        _LOGGER.debug(
-            "Adding WeMo device at %s:%i (%s)",
-            device.host,
-            device.port,
-            device.serialnumber,
-        )
+
+class WemoDispatcher:
+    """Dispatch WeMo devices to the correct platform."""
+
+    def __init__(self, config_entry: ConfigEntry):
+        """Initialize the WemoDispatcher."""
+        self._config_entry = config_entry
+        self._added_serial_numbers = set()
+        self._loaded_components = set()
+
+    @callback
+    def async_add_unique_device(
+        self, hass: HomeAssistant, device: pywemo.WeMoDevice
+    ) -> None:
+        """Add a WeMo device to hass if it has not already been added."""
+        if device.serialnumber in self._added_serial_numbers:
+            return
 
         component = WEMO_MODEL_DISPATCH.get(device.model_name, SWITCH_DOMAIN)
 
@@ -146,11 +154,13 @@ async def async_setup_entry(hass, entry):
         # - Component is being loaded, add to backlog
         # - Component is loaded, backlog is gone, dispatch discovery
 
-        if component not in loaded_components:
+        if component not in self._loaded_components:
             hass.data[DOMAIN]["pending"][component] = [device]
-            loaded_components.add(component)
+            self._loaded_components.add(component)
             hass.async_create_task(
-                hass.config_entries.async_forward_entry_setup(entry, component)
+                hass.config_entries.async_forward_entry_setup(
+                    self._config_entry, component
+                )
             )
 
         elif component in hass.data[DOMAIN]["pending"]:
@@ -163,7 +173,48 @@ async def async_setup_entry(hass, entry):
                 device,
             )
 
-    return True
+        self._added_serial_numbers.add(device.serialnumber)
+
+
+class WemoDiscovery:
+    """Use SSDP to discover WeMo devices."""
+
+    ADDITIONAL_SECONDS_BETWEEN_SCANS = 10
+    MAX_SECONDS_BETWEEN_SCANS = 300
+
+    def __init__(self, hass: HomeAssistant, wemo_dispatcher: WemoDispatcher) -> None:
+        """Initialize the WemoDiscovery."""
+        self._hass = hass
+        self._wemo_dispatcher = wemo_dispatcher
+        self._stop = None
+        self._scan_delay = 0
+
+    async def async_discover_and_schedule(self, *_) -> None:
+        """Periodically scan the network looking for WeMo devices."""
+        _LOGGER.debug("Scanning network for WeMo devices...")
+        try:
+            for device in await self._hass.async_add_executor_job(
+                pywemo.discover_devices
+            ):
+                self._wemo_dispatcher.async_add_unique_device(self._hass, device)
+        finally:
+            # Run discovery more frequently after hass has just started.
+            self._scan_delay = min(
+                self._scan_delay + self.ADDITIONAL_SECONDS_BETWEEN_SCANS,
+                self.MAX_SECONDS_BETWEEN_SCANS,
+            )
+            self._stop = async_call_later(
+                self._hass,
+                self._scan_delay,
+                self.async_discover_and_schedule,
+            )
+
+    @callback
+    def async_stop_discovery(self) -> None:
+        """Stop the periodic background scanning."""
+        if self._stop:
+            self._stop()
+            self._stop = None
 
 
 def validate_static_config(host, port):

tests/components/wemo/conftest.py

@@ -1,4 +1,6 @@
 """Fixtures for pywemo."""
+import asyncio
+
 import pytest
 import pywemo
 
@@ -26,9 +28,11 @@ def pywemo_registry_fixture():
     registry = create_autospec(pywemo.SubscriptionRegistry, instance=True)
 
     registry.callbacks = {}
+    registry.semaphore = asyncio.Semaphore(value=0)
 
     def on_func(device, type_filter, callback):
         registry.callbacks[device.name] = callback
+        registry.semaphore.release()
 
     registry.on.side_effect = on_func
 

tests/components/wemo/test_init.py

@@ -1,9 +1,17 @@
 """Tests for the wemo component."""
-from homeassistant.components.wemo import CONF_DISCOVERY, CONF_STATIC
+from datetime import timedelta
+
+import pywemo
+
+from homeassistant.components.wemo import CONF_DISCOVERY, CONF_STATIC, WemoDiscovery
 from homeassistant.components.wemo.const import DOMAIN
 from homeassistant.setup import async_setup_component
+from homeassistant.util import dt
 
-from .conftest import MOCK_HOST, MOCK_PORT
+from .conftest import MOCK_HOST, MOCK_NAME, MOCK_PORT, MOCK_SERIAL_NUMBER
+
+from tests.async_mock import create_autospec, patch
+from tests.common import async_fire_time_changed
 
 
 async def test_config_no_config(hass):
@@ -87,3 +95,47 @@ async def test_static_config_with_invalid_host(hass):
         },
     )
     assert not setup_success
+
+
+async def test_discovery(hass, pywemo_registry):
+    """Verify that discovery dispatches devices to the platform for setup."""
+
+    def create_device(counter):
+        """Create a unique mock Motion detector device for each counter value."""
+        device = create_autospec(pywemo.Motion, instance=True)
+        device.host = f"{MOCK_HOST}_{counter}"
+        device.port = MOCK_PORT + counter
+        device.name = f"{MOCK_NAME}_{counter}"
+        device.serialnumber = f"{MOCK_SERIAL_NUMBER}_{counter}"
+        device.model_name = "Motion"
+        device.get_state.return_value = 0  # Default to Off
+        return device
+
+    pywemo_devices = [create_device(0), create_device(1)]
+    # Setup the component and start discovery.
+    with patch(
+        "pywemo.discover_devices", return_value=pywemo_devices
+    ) as mock_discovery:
+        assert await async_setup_component(
+            hass, DOMAIN, {DOMAIN: {CONF_DISCOVERY: True}}
+        )
+        await pywemo_registry.semaphore.acquire()  # Returns after platform setup.
+        mock_discovery.assert_called()
+        pywemo_devices.append(create_device(2))
+
+        # Test that discovery runs periodically and the async_dispatcher_send code works.
+        async_fire_time_changed(
+            hass,
+            dt.utcnow()
+            + timedelta(seconds=WemoDiscovery.ADDITIONAL_SECONDS_BETWEEN_SCANS + 1),
+        )
+        await hass.async_block_till_done()
+
+    # Verify that the expected number of devices were setup.
+    entity_reg = await hass.helpers.entity_registry.async_get_registry()
+    entity_entries = list(entity_reg.entities.values())
+    assert len(entity_entries) == 3
+
+    # Verify that hass stops cleanly.
+    await hass.async_stop()
+    await hass.async_block_till_done()